It is no surprise the mayor of London wants to ban wood burning: even new stoves are much more polluting than the exhaust of a heavy goods vehicle

Browse through the home style magazines in your newsagent’s or watch Channel 4’s Grand Designs and you will see beautifully decorated living rooms complete with a roaring fire. Wood burning has become very fashionable and, let’s face it, a log fire is cosy.

Natural gas central heating largely banished solid fuel and brought huge improvements in our urban air. For two decades the UK’s official energy statistics said that home wood burning was too small to be quantified, but under the radar it has been making a return. A 2016 government survey found that 7.5% of UK homes burned wood making up 30% of UK particle emissions. In London, one home in 12 burns wood, but this accounts for more than a quarter of the particle pollution produced in the capital. It is no surprise that the mayor of London, Sadiq Kahn, has called for powers to address this problem.

How you burn wood is important. In London, 69% of people who burn wood are doing so in open fires, a practice banned in the capital by the Clean Air Acts of 1956 and 1968. New stoves pollute far less than open fires, but a recent report found that the limits for Ecodesign wood burners allow six times more particle pollution than the exhaust of a modern heavy goods vehicle, equivalent to 18 new diesel cars.

What you burn matters, too. Construction wood contains harmful metals to prevent rot and woodworm. Old painted wood can contain lead. These are emitted in the smoke. Wet wood is more polluting than dry wood, prompting the Defra-backed Ready to Burn labelling scheme.

We think of wood burning as natural, but experiments show that wood smoke contains shocking levels of harmful particles

Walk round many suburbs on a winter’s night and your nose will tell you that wood burning is being used for home heating. A recent UK government survey found that 7.5% of UK homes now burn wood. The vast majority use it for supplementary heating or decoration. Wood burning is most popular in the south-east where it is used by around 16% of households and it is least popular in northern England and Scotland where it is used by less than 5%.

We think of wood burning as being natural and therefore less harmful to the environment when compared with fossil fuels. However, particle pollution from UK wood burning is now estimated to be more than double diesel exhaust.

Swiss scientists have been investigating what happens to wood smoke once it leaves your chimney. They burnt logs in a stove and collected the smoke in a chamber. UV lights were used to simulate sunlight and they waited. Slowly the particle pollution in the chamber increased, in some cases by up to three times. If this laboratory experiment reflects what happens in our cities; then pollution from wood burning is even greater than we thought.

Setting aside the machinery used in forestry and deliveries, wood burning could be carbon neutral. But carbon dioxide is not the only pollutant that affects our climate. Diesel and coal smoke are well known sources of black carbon that absorbs heat adding to climate change. The smoke and the extra particles that form from wood smoke is brown, which also adds to climate warming.

• The Surgeon General has determined that there is no safe level of exposure to ambient smoke!

• If you smell even a subtle odor of smoke, you are being exposed to poisonous and carcinogenic chemical compounds!

• Even a brief exposure to smoke raises blood pressure, (no matter what your state of health) and can cause blood clotting, stroke, or heart attack in vulnerable people. Even children experience elevated blood pressure when exposed to smoke!

• Since smoke drastically weakens the lungs' immune system, avoiding smoke is one of the best ways to prevent colds, flu, bronchitis, or risk of an even more serious respiratory illness, such as pneumonia or tuberculosis! Does your child have the flu? Chances are they have been exposed to ambient smoke!